Like deleted scenes snipped out of a movie, some sequences in our genes end up on the cutting-room floor, and cells don’t use them to make proteins. Now, two studies find that these segments, known as introns, help yeast survive during hard times. The research uncovers another possible function for a type of DNA that scientists once thought was useless. Introns are prevalent in plants and fungi, as well as in humans and other animals—each of our roughly 20,000 genes carry an average of eight. When one of our cells starts to make a protein from a particular gene, enzymes generate an RNA copy that includes the introns. Next, the cell snips the introns out of the RNA and splices the remaining portions of the molecule back together. This edited RNA molecule then serves as a guide to build the protein.

Was one of your 2019 resolutions a return to the gym? If so, your muscles might be a little sore this time of year. But do you know what recovery methods help muscle soreness? Here’s what the science has to say about popular recovery tools like ice baths, compression tights and regular stretching.

As marijuana use becomes more widespread and varied, some people worry that its more potent versions can cause or exacerbate mental illness. Experts now distinguish between the “new cannabis” — legal, highly potent, available in tabs, edibles and vapes — and the old version, a far milder weed passed around in joints. Levels of THC., the chemical that produces marijuana’s high, have been rising for at least three decades, and it’s now possible in some states to buy vape cartridges containing little but the active ingredient. The concern is focused largely on the link between heavy usage and psychosis in young people. Doctors first suspected a link some 70 years ago, and the evidence has only accumulated since then.